Grain-oriented electrical steel sheet

Abstract

This grain-oriented electrical steel sheet does not have a forsterite film present between a base steel sheet and a tension-insulation coating, in which the base steel sheet contains a predetermined element in a predetermined amount, and in a case in which a cross section perpendicular to a rolling direction of the base steel sheet is viewed, when a region having a length of 10 μm from a surface of the base steel sheet toward the inside of the base steel sheet in a sheet thickness direction of the base steel sheet and a length of 20 mm in a direction perpendicular to the sheet thickness direction is an observation region, needle-like inclusions having a length of 1 μm or more are not present in the observation region.

The invention claimed is: 
     
       1. A grain-oriented electrical steel sheet in which a forsterite film is not present between a base steel sheet and a tension-insulation coating, wherein
 the base steel sheet contains: 
 0.085% by mass or less of C; 
 0.80 to 7.00% by mass of Si; 
 0.05 to 1.00% by mass of Mn: 
 0.065% by mass or less of acid-soluble Al; 
 0.003% by mass or less of S; 
 0.0040% by mass or less of N; 
 0.0005 to 0.0080% by mass of B; 
 0 to 0.50% by mass of P; 
 0 to 1.00% by mass of Ni; 
 0 to 0.30% by mass of Sn; 
 0 to 0.30% by mass of Sb; 
 0 to 0.40% by mass of Cu; 
 0 to 0.30% by mass of Cr; 
 0 to 0.01% by mass of Bi; and 
 a remainder of Fe and impurities as a chemical composition thereof, and 
 in a case in which a cross section perpendicular to a rolling direction of the base steel sheet is viewed, when a region having a length of 10 μm from a surface of the base steel sheet toward the inside of the base steel sheet in a sheet thickness direction of the base steel sheet and a length of 20 mm in a direction perpendicular to the sheet thickness direction is an observation region, needle-like inclusions having a length of 1 μm or more are not present in the observation region. 
 
     
     
       2. The grain-oriented electrical steel sheet according to  claim 1 , wherein the needle-like inclusion contains mullite represented by 3Al 2 O 3 ·2SiO 2 .